Fig. 7. Distinct expression patterns of cyclin D1 and p130 in different chondrocyte zones and their regulation by Wnt5a and Wnt5b. (A) In the developing cartilage of a wild-type embryo at 18.5 dpc, p130 was expressed at a higher level in Zone I (double headed arrows) and differentiated chondrocytes (arrow), but cyclin D1 was expressed at a higher level in Zone II chondrocytes. In the Wnt5a^-/- cartilage, cyclin D1 expression was decreased and Zone I was reduced. When Ihh was overexpressed in chondrocytes in the Col2a1-Gal4; Uas-Ihh embryo, cyclin D1 expression was increased in Zone II but p130 expression in Zone I was not affected. When Ihh was overexpressed in the Wnt5a^-/-; Col2a1-Gal4; Uas-Ihh mouse, cyclin D1 expression was elevated and Zone I region was increased when compared with the Wnt5a^-/- mutant mouse. (B) Cyclin D1 expression was reduced by Wnt5a overexpression in the Col2a1-Wnt5a embryo (above, 18.5 dpc), but increased by Wnt5b overexpression in the Col2a1-Wnt5b embryo (below, 17.5 dpc). (C) The zone with higher p130 expression (double headed arrows) was expanded in the Col2a1-Wnt5a embryo (above, 18.5 dpc), but reduced in the Col2a1-Wnt5b embryo (below, 17.5 dpc).

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